U.S. Pat. Nos. 3,517,480 and 3,603,058 illustrate and describe machines for the production of composite cigarette filters by directly flowing granular filter material from a storage hopper into a vertically oriented filter tube made of paper. Similarly, US Patent Application Publication 2002/0119874A1 describes another machine for producing compound cigarette filters that includes a series of rotating plates with cavities therein into which the granular filter material is deposited. The cavities ultimately are aligned with an open paper ended filter tube to facilitate deposit of the granular material into the tube. These machines have the disadvantage of often destroying the integrity of the paper filter tubes into which filter materials are deposited. They also deposit imprecise amounts of granular material and produce undesired amounts of fine dust and the like.
US Patent Application Publication 2006/0112963 discloses a process and apparatus for producing compound cigarette filters which preserve the integrity of the paper filter tubes of cigarette filters and provide precise deposition of granular material into the filters. The process and apparatus function to deposit granular filter material into the open ends of vertically oriented filter tubes. Predetermined amounts of diverse granular material are withdrawn by suction from sources of such material, and these amounts are deposited into the tubes. Solid filter segments seal the granular material within the tube. After one half of each filter tube is filled with granular material and sealed, the tube is inverted and the opposite end is filled in substantially the same manner. When cut in half, each filter tube produces two cigarette filters. Further improvements over the process and apparatus of US Patent Application Publication 2006/0112963 are desired.